[Elecraft] [MM] W2 review - and why the diode...

[Richard Squire - HB9ANM]

Hello David

Why the diode? Well, any relay driven by a solid-state device should have a
diode across its coil (in reverse polarity!) to short reverse voltage
spikes. Transistor are rather fast switches... and such spikes would damage
them. Never drive a relay from a transistor or IC without such a parallel
diode!
73
Richard - HB9ANM


David Ferrington, M0XDF wrote:
> 
> Now that's a good idea. Why the diode?
> 73 de M0XDF, K3 #174
> --  
> The soul is the same in all living creatures, although the body is
> different. -Hippocrates, physician (460-c.377 BCE)
> 
> On 14 Nov 2009, at 08:31, AD6XY wrote:
> 
>> My K3 12V output powers an automotive relay (+diode) which connects  
>> the 12V
>> PSU to an 8 way powerpole panel. This allows me to control the power  
>> to the
>> LP-100A, the transverters, the KRC2 and an AT-1000pro with the K3  
>> power
>> switch.
> 
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-----
Richard - HB9ANM
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